The present invention relates to self-contained power cells capable of supplying electrical energy, and more particularly to a compact energy source capable of supplying a low level of energy for a relatively long period of time.
Electric power cells provide self-contained sources of electrical energy for driving external loads. Chemical batteries are a common example of a practical electric power cells, in that they are relatively inexpensive to produce and capable of supplying a reasonably high energy output, even though it may be for a relatively short period of time. These batteries are effectively employed in a large variety of applications and environments, which can range in requirements from a very large current demand over a short period of time, such as a heavy-duty fork lift truck, to a small current demand over a long period of time, such as a small wristwatch. While chemical batteries are very effective at providing the power needs of such devices, the size and durational requirements sometimes associated with microelectronic devices are not always compatible with employment of chemical batteries. One example of a microelectronic device possibly requiring a compact, long-life, low-current battery is a nonvolatile memory circuit of a compact computing device. Another example is a low-power electronic sensor which is intended for long term unattended operation in an inaccessible location.
The amount of electrical energy supplied by chemical batteries is directly related to the mass of reactive materials incorporated in the chemical batteries. This characteristic can result in the size of a chemical battery being much larger than its load. Even a chemical battery in a modern electronic wristwatch is usually much larger in size and heavier relative to the electronic microchip circuitry which drives the watch. It is therefore desirable to provide a battery that can fit in a very small space, and preferably one which can also provide many years of uninterrupted service.